Field of the Invention
This disclosure pertains in general to determine a concentration of gaseous content in a container with non-well defined outer geometry. More particularly the disclosure relates to gas absorption spectroscopy of gaseous content in a container. Especially the disclosure relates to determining or calibrate for an optical path length in containers with at least one flexible or variable wall which is optically transparent or translucent.
Background of the Disclosure
Optical absorption spectroscopy is an established method to measure gaseous species inside containers, in a non-invasive and non-destructive manner. In traditional analysis, the procedure requires that the optical path length in the volume containing the gaseous species to be measured is well defined, which can be accomplished e.g. by using special purpose containers (vials) with optical grade transparent walls and known distance between the walls. However, there is a great need in certain applications to be able to monitor or quantify the gases inside containers that have not been designed for the purpose of spectroscopic measurements. Examples of such applications include packages of foodstuffs that utilize modified atmosphere packaging (MAP) to prolong or ensure longevity. Such packages are normally not designed with spectroscopic analysis in mind and may be made of flexible or soft materials. It is desired to measure the gaseous content of such containers for the purposes of process control and quality control. Similar applications exist in the areas of packaging of pharmaceuticals and other medical products. Such measurements may be carried out either manually or in an automated manner in a production or transport logistics line.
Hence, new improved apparatus and methods for determining an optical path length in such containers would be advantageous.